linux-kernel - Re: [PATCH] ACPI / sysfs: Extend ACPI sysfs to provide access to boot error region

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Message-ID: <CAGXu5jLXGwbzxMEfbe-aaRos_kxnpnhOuErJx1j2qNwZvZZTag@mail.gmail.com>
Date:   Mon, 28 Aug 2017 17:10:33 -0700
From:   Kees Cook <keescook@...gle.com>
To:     "Luck, Tony" <tony.luck@...el.com>
Cc:     Alan Cox <gnomes@...rguk.ukuu.org.uk>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>, Boris Petkov <bp@...e.de>,
        Tyler Baicar <tbaicar@...eaurora.org>,
        Punit Agrawal <punit.agrawal@....com>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ACPI / sysfs: Extend ACPI sysfs to provide access to boot
 error region

On Wed, Aug 23, 2017 at 7:56 AM, Luck, Tony <tony.luck@...el.com> wrote:
>>> Should this not also have a capability check. Assuming file permissions
>>> are sufficient for grabbing a chunk of system memory holding error
>>> info doesn't seem too scary but it's at odds with a lot of other cases ?
>>
>> At least one of those other cases (pstore) added a capability check and now regret
>> it.  There's a thread on reverting it. Look for:
>>
>>   Revert "pstore: Honor dmesg_restrict sysctl on dmesg dumps"
>
> Here's at least part of that thread:
>
> https://marc.info/?l=linux-kernel&m=150301241114262&w=2
>
> Kees: you were OK with removing the capability check from pstore, right?

Yeah, as long as there is comparable protections.

-Kees

-- 
Kees Cook
Pixel Security